This invention relates to novel compositions of macrolide avermectin and milbemycin endecticides with an immunising agent and in particular it relates to a stable injectable composition for use with warm-blooded animals, in particular ruminants.
The use of a combination of an parasitic agent and immunising agent as a single injectable formulation offers advantages both in time and cost saving to the farmer.
New Zealand Patent Nos. 191413 and 193807 of ICI Tasman Limited disclose water based formulations of D, L-tetramisole and clostridial vaccine in the treatment of helminthiasis and clostridial diseases in warm-blooded animals. Both D, L-tetramisole and the clostridial vaccine are water soluble hence a combination of the two is straight forward. What was surprising was that the clostridial vaccine remained effective at a pH lower than 6.0 and that the combination improved the immune response in ruminants, though not in other animals.
These aqueous formulations commonly used an adjuvant such as alum or alum hydroxide to enhance the effect of the antigen. Such adjuvants are usually included in the formulation as an aqueous suspensions. The vaccines can then be readily mixed with water based anthelmintic formulations.
Since the use of D, L-tetramisole and more particularly the L-isomer levamisole, there have been a number of other potent antiparasitic macrocyclic lactone compounds such as the avermectins, ivermectin, doramectin, abamectin, milbemycin, moxidectin used in the treatment of diseases in warm blooded animals. These later parasiticides are insoluble in water which creates difficulties in formulating stable injectable compositions. However, the compounds have the advantage that they are active against internal and external parasites in domestic animals.
Formulations are therefore based on co-solvent systems or aqueous solvent systems utilising a water-soluble solvent with one or more wetting agents. Water soluble solvents mix readily with traditional aqueous adjuvant systems to form combinations of anthelmintics and vaccines. This is not the case with oil based (non-aqueous) systems.
It is an object of the invention to provide an improved injectable composition combining a parasitic agent and an antigen or at least one that provides the public with a useful choice.
It has been surprisingly discovered that non-aqueous anthelmintics can be combined with an antigen using an oil as an adjuvant and carrier to give a stable formulation that can be safely injected into warm blooded animals including cattle and sheep.
In one aspect the invention comprises a stable injectable composition comprising a non-aqueous parasitic agent in a therapeutically effect amount and an antigen in combination with a liquid carrier that also acts as an adjuvant for use with warm blooded animals.
Preferably the non-aqueous parasitic agent is a macrolide compound selected from group comprising avermectin, ivermectin, doramectin, abamectin, milbemycin and moxidectin, present in from 0.05 to 10% w/v.
More preferably the non-aqueous parasitic agent is chosen from the group comprising abamectin, ivermectin. moxidectin and doramectin.
Preferably, the carrier is an oil, either a vegetable oil such as sesame oil, saponine oil, soya bean oil, and corn oil or a mineral adjuvant oil, such as paraffin oil, or purified derivatives of vegetable or mineral oils, such as quiala, which is suitable for injection into animals or a mixture thereof. The oil acts as an adjuvant for the immunising agent and may also act as a solvent for the anthelmintic. The oil also extends the action of the parasitic agent.
Additionally, the composition may further contain an oil soluble solvent. The oil soluble solvent is chosen from the group comprising alcohols having four or more carbon atoms for example benzyl alcohol, ethylbenzyl alcohol, phenethyl alcohol and other aromatic monohydric alcohols.
Preferably the alcohol is present in the range from 10-50 w/v %.
The antigen is incorporated into the composition by emulsifying it in a suitable emulsion agent, for example sorbiten oleate (Span 80(trademark) or Liposorb 80(trademark)). Other suitable emulsion agents may also be used. The emulsifier is present in the range of from 5-50 w/v %.
Antigens suitable to be used in the compositions include antigens derived from bacterial and viral pathogens of warm-blooded animals. Preferably the antigen is chosen from the group comprising antigens derived from and toxins of clostridial diseases including Clostridium septicum, Clostridium tetani, Clostridium chauvoei, Clostridium novyi, Clostridium sordelli and Clostridium haemolytica. Other possible antigens include Pasteurella, Pasteurella maltocida and Corynebacterium pseudotuberculosis and viral antigens for Infectious Bovine Rhinotracheitis, Bovine Viral Diarrhoea and Parainfluenza.
In another aspect, the invention comprises a method of treating parasitic diseases and preventing viral and bacterial diseases in warm blooded animals by administration to an animal of a composition as described above.
Preferably the composition is administered to the animal by injecting the animal.
Preferably the composition is administered at the rate of 0.5-5 mL/50 kg bodyweight of the animal.